1. Field of the Invention
This invention relates to a shutter mechanism for a motion picture camera, and more particularly to a rotary shutter for a motion picture camera the open angle of which can be changed.
2. Description of the Prior Art
In a rotary shutter comprising a rotatable sector which closes the aperture of the camera when the film is fed and opens the aperture when the film is stopped to expose the film to the light incident through the taking lens of the camera, the angle of the open portion of the sector determines the exposure time. The angle of the open portion of the sector (hereinafter referred to simply as "open angle") is usually about 160.degree. in the conventional motion picture camera using a film of 8 mm wide. Recently, motion picture cameras having a rotary shutter which has an open angle of as large as 230.degree. have been developed to enable taking a motion picture in the dark.
This kind of motion picture cameras having a rotary shutter of large open angle are advantageous in taking motion pictures in the dark, but are disadvantageous when used in the presence of large amount of light since it is difficult to accurately control the exposure with a small diaphragm. When the scene is bright, the aperture must be stopped down to a great extent to make a proper exposure of the film with the large open angle of the rotary shutter. The control of the exposure is very difficult when the aperture size is substantially small. In addition, if the open angle is very large, the shutter speed is very slow and accordingly the image is apt to be blurred.
It has also been known in the art to continuously vary the open angle of a rotatable shutter to effect a fade-in and fade-out operations. This type of rotatable shutter is, however, very complicated in structure and considerably expensive, accordingly.